It is not just the large front baffle and space requirement that works against OB, they do not go as deep bass-wise because of the lack of reinforcement and because of out of phase cancellation. I personally don't give ultra deep bass a high priority, so OB speakers are attractive, but, the market seems to really put such a premium on ultra deep bass--hence the use of subwoofers, popularity of high wattage solid state amps that can deliver bass punch, etc.
A lot of the modern speakers with their very narrow front profiles sound the way they look, to me--thin and lacking is weight. I do wonder if not enough concern is given to baffle-step and diffraction issues with some of these thin baffle designs.